time T

1. An unspecified but usually
well-understood time, often used in conjunction with a later time
T+1. "We'll meet on campus at time T or at Louie's
at time T+1" means, in the context of going out for dinner:
"We can meet on campus and go to Louie's, or we can meet at
Louie's itself a bit later." (Louie's was a Chinese restaurant in
Palo Alto that was a favorite with hackers.) Had the number 30
been used instead of the number 1, it would have implied that the
travel time from campus to Louie's is 30 minutes; whatever time
T is (and that hasn't been decided on yet), you can meet
half an hour later at Louie's than you could on campus and end up
eating at the same time. See also since time T equals minus infinity.